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Reading Huge input from the terminal in least time.

This is a discussion on Reading Huge input from the terminal in least time. within the C Programming forums, part of the General Programming Boards category; Hi there, Suppose we have a 2-d array arr[1000][1000] and input is supplied one row at a time, Then what ...

  1. #1
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    Reading Huge input from the terminal in least time.

    Hi there,
    Suppose we have a 2-d array arr[1000][1000] and input is supplied one row at a time, Then what is the best possible way to read this much data in the least time as scanf() take too much time in reading from the keyboard.

  2. #2
    ATH0 quzah's Avatar
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    Typing a million of anything is going to take too much time.

    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
    and the hat of int overfl Salem's Avatar
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    What do you mean "too much time".
    Sure, it'll take a lot of time if you're typing them in.

    But to read from a file, using redirection, takes almost no time at all.
    Code:
    Generate 1M numbers to test with
    $ perl -e 'for($i=0;$i<1000000;$i++){print int(rand()*1000) . "\n";};' > 1m.txt
    
    Less than 0.5 seconds, on this <2GHz laptop
    $ time ./a.out < 1m.txt 
    
    real	0m0.362s
    user	0m0.356s
    sys	0m0.008s
    
    The simple test code
    $ cat bar.c
    #include <stdio.h>
    int main ( ) {
      int foo;
      while ( scanf("%d",&foo) == 1 ) {
      }
      return 0;
    }
    Perhaps you should show us what you actually did, rather than just complain "it's too slow" without backing it up with some evidence.
    vart likes this.
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